One might think that the era of the injection test benches has come to an end. However, if you go to the page injection nozzle test and click on the second picture, you can see a test bench with Common Rail-equipment. Regardless of whether they only have a future in research laboratories or not, for a sensible overhauling of in-line fuel injection pumps, the test bench was, and still is, indispensible.
First of all, this type of test bench needs a strong, and for the largest types, for the big in-line pumps, a very strong drive mechanism. It's not unusual for these to have the same performance as small car engines. For this reason they are driven by three-phase-current. The price of such equipment is largely dependant on the strength of the electric motor. There are any number of adapters available for the mounting of pumps of various origin. These pumps then behave as if they were driven by diesel engines, and deliver fuel, at high pressure to the individual nozzles. The fuel is sprayed into test-tubes, whereby, under normal circumstances, the spray pattern can not be seen. All possible tests are carried out, strictly according to the test plan, whereby, both the relative as well as the absolute allocation of the injection volume of the individual cylinders to each other is exactly adjusted. In addition, importance is also placed on the exact timing of the injection starting point to the individual cylinders. This can also be adjusted on the in-line pump. In the end, the injection pump is comprehensively tested and can - with the correct start of fuel delivery - be installed in the diesel engine. Thanks to the relatively complex procedure, a favourable performance together with a corresponding fuel consumption and particularly, a very low soot development can be achieved. In the above picture, an injection pump test bench, which has been converted for training purposes, can be seen. In this case with a distribution type injection pump, where generally, there is nothing to adjust. There are weights attached to the flywheel, which together with the appropriate inductive pick-up, supply sufficient signals. Thus, an electronic diesel injection regulation can be installed on the test bench. Thereby, the equipment functions as if it were installed in the vehicle. At this opportunity, one discovers that the noise level of an injection device alone, lies pretty close to that of the diesel engine itself.